Differences between abstract class and concrete class in Java

JavaObject Oriented ProgrammingProgramming

In Java, abstraction is achieved using Abstract classes and interfaces. An abstract class contains abstract methods which a child class. Following are the important differences between abstract class and a concrete class.

Sr. No.
Key
Abstract Class
Concrete Class
1
Supported Methods
Abstract class can have both an abstract as well as concrete methods.
A concrete class can only have concrete methods. Even a single abstract method makes the class abstract.
2
Instantiation
Abstract class can not be instantiated using new keyword.
Concrete class can be instantiated using new keyword.
3
Abstract method
Abstract class may or may not have abstract methods.
Concrete clas can not have an abstract method.
4
Final
Abstract class can not be declared as a final class.
Concrete class can be declared final.
5
Keyword
Abstract class declared using abstract keyword.
Concrete class is not having abstract keyword during declaration.
6
Inheritance
Abstract class can inherit another class using extends keyword and implement an interface.
Interface can inherit only an inteface.
7
Interface
Abstract class can not implement an interface alone. A child class is needed to be able to use the interface for instantiation.
Interface can be implemented easily.

Example of Abstract Class vs Concrete Class

JavaTester.java

public class JavaTester {
   public static void main(String args[]) {
      Cat lion = new Lion();
      lion.eat();
   }
}
abstract class Cat {
   abstract public void eat();
}
class Lion extends Cat{
   public void eat(){
      System.out.println("Lion eats");
   }
}

Output

Lion eats
raja
Published on 26-Nov-2019 14:40:18
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